In roll-up type doors used for closing the loading doorway of trucks, vans or the like, it has been common practice to provide a mechanism which will assist the manual opening of the door. In one such mechanism, a torsion spring is mounted on a shaft which is located in the header cavity found between the header and the path along which the door is driven when it is being raised This mechanism only provides an assistance during the opening of the door and it acts as somewhat of a resistance to the closing of the door. It is not a mechanism which acts to power the door to an open position or a closed position.
The doors which are used on vans and trucks and the like can be relatively heavy in weight, particularly when the door is constructed to provide security against theft. For this reason, attempts have been made to provide a powered door which can be driven between its open and its closed position by a power source mounted within the container body.
Because more power is required in order to open a roll-up door than is required in order to close a roll-up door, the power source used for this type of roll-up door is generally the type of power source used for opening and closing garage doors. These mechanisms include a motor which is suspended below the roof of the container space ahead of the position in which the upper edge of the door will be located when the door is in the fully open position. A ram or chain driven mechanism is provided which connects the power source to the upper edge of the door so that when the door is to be opened, the ram is activated to pull the door along the guide track by applying the pulling force to the uppermost door panel. This type of powered mechanism is effective when used for the purposes of closing the door, however, difficulty is frequently experienced in attempting to open a door because the forces applied during opening are also applied directly to the upper door panel.
The manner in which a conventional door opening mechanism is mounted below the roof of a container body has a number of distinct disadvantages. Firstly, it occupies space which might otherwise be used for the purposes of carrying a payload and it therefore reduces the carrying capacity of the vehicle. In addition, because it is exposed on the underside of the ceiling, it is easily damaged by vehicles such as forklift trucks and the like which are driven into and out of container bodies during loading and unloading.
We have found that the difficulties of the prior art described above can be overcome by providing in a container body a winch mechanism which is located in the header cavity and which includes separate winding means for raising and lowering the door. The winding means used for raising the door is connected to the lower end of the door and the winding means used for lowering the door is connected to the upper end of the door so that the door can be raised or lowered.
A further difficulty which has been experienced in the design of articulated doors is that of ensuring that the panel which is the last panel to be positioned in a closing position is fully located in the same plane as the preceding panels so as to present a flat closed door. The guide track which guides the door panels usually includes a curved portion located closely adjacent the upper end of the door opening. In order to ensure that the upper most panel is located in the required closed position, it is customary to use offset support brackets for supporting the guide rollers of the last door panel so that the last door panel will assume the planar closed position even when its associated guide roller is positioned on the curved portion of the guide track. It is preferable to locate said guide roller in the curved portion of the guide track as this facilitates the initial movement of its associated door panel during the early stages of the opening of the door. This "offset" is, however, a permanent offset and as a consequence, it is necessary to provide a substantial clearance between the guide track and the adjacent wall of the storage space so that the door panel which is mounted on the offset guide roller can clear the adjacent wall. This again results in a loss of useful payload space in vans and the like.
We have found that it is possible to locate the last door panel in the required plane while maintaining its associated roller on a curved portion of the guide track without requiring a permanent offset by mounting the roller on a hinged support bracket. By using a hinged support bracket, it is possible to obtain the required planar closure while maintaining the roller associated with the last door panel on the curved portion of the guide track without requiring to provide a special clearance to accommodate the last door panel.
A further difficulty which has been experienced in roll-up doors of vans and the like is that it has been customary to use large metal hinges to connect the door panels. These hinges are unsightly and frequently become corroded. Even if these hinges are located with their hinge pins on the inside of the door, they are customarily attached to the door by bolts which extend through the door panels. These bolts tend to rust and again provide an unsightly appearance and in time will weaken.
We have found that it is possible to provide a hinge for connecting adjacent rollers which includes first and second hinge members each of which have a U-shaped channel for receiving adjacent edges of a door and each of which has hinge tubes which can be aligned one with the other and secured by means of a hinge pin.
Difficulty has also been experienced in attempting to provide an effective seal for sealing the edges of a roll-up door of a van or the like.
We have found that an effective seal can be provided by providing a flexible sealing member which is connected to each jamb and is arranged to bear against adjacent marginal edge portions of the outer face of the door when it is in the closed position.
The controls required for controlling the raising and lowering of a roll-up door or the like are preferably simple and inexpensive. We have found that we can provide a simple push-button control mechanism which is capable of providing an automatic shut-off when the door reaches its limit either fully open or fully closed. The control system also incorporates a security system to prevent unauthorized use.
In addition, we have provided a system which can have controls located in the driver compartment of the vehicle and at a point adjacent the exterior of the door or any other point such as inside the load storage compartment.